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Hettler S, Furqan M, Arenal R. Support-Based Transfer and Contacting of Individual Nanomaterials for In Situ Nanoscale Investigations. SMALL METHODS 2024:e2400034. [PMID: 38470226 DOI: 10.1002/smtd.202400034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 02/22/2024] [Indexed: 03/13/2024]
Abstract
Although in situ transmission electron microscopy (TEM) of nanomaterials has been gaining importance in recent years, difficulties in sample preparation have limited the number of studies on electrical properties. Here, a support-based preparation method of individual 1D and 2D materials is presented, which yields a reproducible sample transfer for electrical investigation by in situ TEM. A mechanically rigid support grid facilitates the transfer and contacting to in situ chips by focused ion beam with minimum damage and contamination. The transfer quality is assessed by exemplary specimens of different nanomaterials, including a monolayer of WS2 . Possible studies concern the interplay between structural properties and electrical characteristics on the individual nanomaterial level as well as failure analysis under electrical current or studies of electromigration, Joule heating, and related effects. The TEM measurements can be enriched by additional correlative microscopy and spectroscopy carried out on the identical object with techniques that allow a characterization with a spatial resolution in the range of a few microns. Although developed for in situ TEM, the present transfer method is also applicable to transferring nanomaterials to similar chips for performing further studies or even for using them in potential electrical/optoelectronic/sensing devices.
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Affiliation(s)
- Simon Hettler
- Laboratorio de Microscopías Avanzadas (LMA), Universidad de Zaragoza, Zaragoza, 50018, Spain
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza, 50009, Spain
| | - Mohammad Furqan
- Laboratorio de Microscopías Avanzadas (LMA), Universidad de Zaragoza, Zaragoza, 50018, Spain
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza, 50009, Spain
| | - Raul Arenal
- Laboratorio de Microscopías Avanzadas (LMA), Universidad de Zaragoza, Zaragoza, 50018, Spain
- Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza, 50009, Spain
- ARAID Foundation, Zaragoza, 50018, Spain
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2
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Shen X, Li P, Guo P, Yu KM. On-wire bandgap engineering via a magnetic-pulled CVD approach and optoelectronic applications of one-dimensional nanostructures. NANOTECHNOLOGY 2022; 33:432002. [PMID: 35816940 DOI: 10.1088/1361-6528/ac800b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
Since the emergence of one-dimensional nanostructures, in particular the bandgap-graded semiconductor nanowires/ribbons or heterostructures, lots of attentions have been devoted to unraveling their intriguing properties and finding applications for future developments in optical communications and integrated optoelectronic devices. In particular, the ability to modulate the bandgap along a single nanostructure greatly enhances their functionalities in optoelectronics, and hence these studies are essential to pave the way for future high-integrated devices and circuits. Herein, we focus on a brief review on recent advances about the synthesis through a magnetic-pulled chemical vapor deposition approach, crystal structure and the unique optical and electronic properties of on-nanostructures semiconductors, including axial nanowire heterostructures, asymmetrical/symmetric bandgap gradient nanowires, lateral heterostructure nanoribbons, lateral bandgap graded ribbons. Moreover, recent developments in applications using low-dimensional bandgap modulated structures, especially in bandgap-graded nanowires and heterostructures, are summarized, including multicolor lasers, waveguides, white-light sources, photodetectors, and spectrometers, where the main strategies and unique features are addressed. Finally, future outlook and perspectives for the current challenges and the future opportunities of one-dimensional nanostructures with bandgap engineering are discussed to provide a roadmap future development in the field.
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Affiliation(s)
- Xia Shen
- College of Physics and Optoelectronics, Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, People's Republic of China
| | - Pu Li
- College of Physics and Optoelectronics, Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, People's Republic of China
| | - Pengfei Guo
- College of Physics and Optoelectronics, Key Laboratory of Advanced Transducers and Intelligent Control System Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, People's Republic of China
| | - Kin Man Yu
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong 999077, People's Republic of China
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3
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Tan CS, Huang MH. Surface-dependent band structure variations and bond deviations of GaN. Phys Chem Chem Phys 2022; 24:9135-9140. [PMID: 35403651 DOI: 10.1039/d2cp00100d] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Density functional theory (DFT) calculations on a tunable number of GaN (0001) planes give an invariant band structure, density of states (DOS) diagram, and band gap of the GaN unit cell. Dissimilar band structures and DOS diagrams are obtained for 1, 3, 5, 7, and 9 layers of GaN (101̄0) planes, but the same band structure as that of the (0001) plane returns for 2, 4, 6, and 8 (101̄0) planes. Furthermore, 1 to 4 layers of GaN (101̄1) planes exhibit dissimilar band structures, but the GaN unit cell band structure is obtained for 5 (101̄1) planes. While there are no changes to the Ga-N bond length and bond geometry for the (0001) planes, the (101̄0) planes present bond length variation and bond distortion with odd numbers of layers. Bond length and bond direction deviations are also obtained for 1 to 4 (101̄1) planes. These results suggest that slight structural deviations may be present near the GaN surface to produce facet-dependent properties, and such atomic position deviations in the surface layer can be observed in various semiconductors.
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Affiliation(s)
- Chih-Shan Tan
- Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu 300093, Taiwan.
| | - Michael H Huang
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan.
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4
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Spies M, Sadre Momtaz Z, Lähnemann J, Anh Luong M, Fernandez B, Fournier T, Monroy E, I den Hertog M. Correlated and in-situ electrical transmission electron microscopy studies and related membrane-chip fabrication. NANOTECHNOLOGY 2020; 31:472001. [PMID: 32503014 DOI: 10.1088/1361-6528/ab99f0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Understanding the interplay between the structure, composition and opto-electronic properties of semiconductor nano-objects requires combining transmission electron microscopy (TEM) based techniques with electrical and optical measurements on the very same specimen. Recent developments in TEM technologies allow not only the identification and in-situ electrical characterization of a particular object, but also the direct visualization of its modification in-situ by techniques such as Joule heating. Over the past years, we have carried out a number of studies in these fields that are reviewed in this contribution. In particular, we discuss here i) correlated studies where the same unique object is characterized electro-optically and by TEM, ii) in-situ Joule heating studies where a solid-state metal-semiconductor reaction is monitored in the TEM, and iii) in-situ biasing studies to better understand the electrical properties of contacted single nanowires. In addition, we provide detailed fabrication steps for the silicon nitride membrane-chips crucial to these correlated and in-situ measurements.
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5
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Sistani M, Bartmann MG, Güsken NA, Oulton RF, Keshmiri H, Luong MA, Momtaz ZS, Den Hertog MI, Lugstein A. Plasmon-Driven Hot Electron Transfer at Atomically Sharp Metal-Semiconductor Nanojunctions. ACS PHOTONICS 2020; 7:1642-1648. [PMID: 32685608 PMCID: PMC7366502 DOI: 10.1021/acsphotonics.0c00557] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Indexed: 05/23/2023]
Abstract
Recent advances in guiding and localizing light at the nanoscale exposed the enormous potential of ultrascaled plasmonic devices. In this context, the decay of surface plasmons to hot carriers triggers a variety of applications in boosting the efficiency of energy-harvesting, photocatalysis, and photodetection. However, a detailed understanding of plasmonic hot carrier generation and, particularly, the transfer at metal-semiconductor interfaces is still elusive. In this paper, we introduce a monolithic metal-semiconductor (Al-Ge) heterostructure device, providing a platform to examine surface plasmon decay and hot electron transfer at an atomically sharp Schottky nanojunction. The gated metal-semiconductor heterojunction device features electrostatic control of the Schottky barrier height at the Al-Ge interface, enabling hot electron filtering. The ability of momentum matching and to control the energy distribution of plasmon-driven hot electron injection is demonstrated by controlling the interband electron transfer in Ge, leading to negative differential resistance.
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Affiliation(s)
- Masiar Sistani
- Institute of Solid
State Electronics, Technische Universität
Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
| | - Maximilian G. Bartmann
- Institute of Solid
State Electronics, Technische Universität
Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
| | - Nicholas A. Güsken
- The Blackett Laboratory,
Department of Physics, Imperial College
London, London SW7 2AZ, United Kingdom
| | - Rupert F. Oulton
- The Blackett Laboratory,
Department of Physics, Imperial College
London, London SW7 2AZ, United Kingdom
| | - Hamid Keshmiri
- Institute of Solid
State Electronics, Technische Universität
Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
| | - Minh Anh Luong
- Univ. Grenoble Alpes, CEA, INAC, MEM, F-38000 Grenoble, France
| | - Zahra Sadre Momtaz
- Institut NEEL CNRS/UGA UPR2940, 25 avenue des Martyrs, F-38042 Grenoble, France
| | | | - Alois Lugstein
- Institute of Solid
State Electronics, Technische Universität
Wien, Gußhausstraße 25-25a, 1040 Vienna, Austria
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6
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Brubaker MD, Roshko A, Berweger S, Blanchard PT, Little CAE, Harvey TE, Sanford NA, Bertness KA. Crystallographic polarity measurements in two-terminal GaN nanowire devices by lateral piezoresponse force microscopy. NANOTECHNOLOGY 2020; 31:424002. [PMID: 32580185 DOI: 10.1088/1361-6528/ab9fb2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Lateral piezoresponse force microscopy (L-PFM) is demonstrated as a reliable method for determining the crystallographic polarity of individual, dispersed GaN nanowires that were functional components in electrical test structures. In contrast to PFM measurements of vertically oriented (as-grown) nanowires, where a biased probe tip couples to out-of-plane deformations through the d33 piezoelectic coefficient, the L-PFM measurements in this study were implemented on horizontally oriented nanowires that coupled to shear deformations through the d15 coefficient. L-PFM phase-polarity relationships were determined experimentally using a bulk m-plane GaN sample with a known [0001] direction and further indicated that the sign of the d15 piezoelectric coefficient was negative. L-PFM phase images successfully revealed the in-plane [0001] orientation of self-assembed GaN nanowires as part of a growth polarity study and results were validated against scanning transmission electron microscopy lattice images. Combined characterization of electrical properties and crystallographic polarity was also implemented for two-terminal GaN/Al0.1Ga0.9N/GaN nanowires devices, demonstrating L-PFM measurements as a viable tool for assessing correlations between device rectification and polarization-induced band bending.
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Affiliation(s)
- Matt D Brubaker
- Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO, United States of America
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7
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Spies M, Ajay A, Monroy E, Gayral B, den Hertog MI. Correlated Electro-Optical and Structural Study of Electrically Tunable Nanowire Quantum Dot Emitters. NANO LETTERS 2020; 20:314-319. [PMID: 31851824 DOI: 10.1021/acs.nanolett.9b03858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Quantum dots inserted in semiconducting nanowires are an interesting platform for the fabrication of single photon devices. To fully understand the physical properties of these objects, we need to correlate the optical, transport, and structural properties on the same nanostructure. In this work, we study the spectral tunability of the emission of a single quantum dot in a GaN nanowire by applying external bias. The nanowires are dispersed and contacted on electron beam transparent Si3N4 membranes, so that transmission electron microscopy observations, photocurrent, and micro-photoluminescence measurements under bias can be performed on the same specimen. The emission from a single dot blue or red shifts when the external electric field compensates or enhances the internal electric field generated by the spontaneous and piezoelectric polarization. A detailed study of two nanowire specimens emitting at 327.5 and 307.5 nm shows spectral shifts at rates of 20 and 12 meV/V, respectively. Theoretical calculations facilitated by the modeling of the exact heterostructure provide a good description of the experimental observations. When the bias-induced band bending is strong enough to favor tunneling of the electron in the dot toward the stem or the cap, the spectral shift saturates and additional transitions associated with charged excitons can be observed.
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Affiliation(s)
- Maria Spies
- Univ. Grenoble-Alpes, CNRS, Institut Néel , 25 av. des Martyrs , 38000 Grenoble , France
| | - Akhil Ajay
- Univ. Grenoble-Alpes, CEA, IRIG-PHELIQS-NPSC , 17 av. des Martyrs , 38000 Grenoble , France
| | - Eva Monroy
- Univ. Grenoble-Alpes, CEA, IRIG-PHELIQS-NPSC , 17 av. des Martyrs , 38000 Grenoble , France
| | - Bruno Gayral
- Univ. Grenoble-Alpes, CEA, IRIG-PHELIQS-NPSC , 17 av. des Martyrs , 38000 Grenoble , France
| | - Martien I den Hertog
- Univ. Grenoble-Alpes, CNRS, Institut Néel , 25 av. des Martyrs , 38000 Grenoble , France
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8
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Li Z, Zhang L, Liu Y, Shao C, Gao Y, Fan F, Wang J, Li J, Yan J, Li R, Li C. Surface‐Polarity‐Induced Spatial Charge Separation Boosts Photocatalytic Overall Water Splitting on GaN Nanorod Arrays. Angew Chem Int Ed Engl 2020; 59:935-942. [DOI: 10.1002/anie.201912844] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Zheng Li
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Liang Zhang
- Semiconductor Lighting Technology Research and Development CenterInstitute of SemiconductorsChinese Academy of Sciences Beijing 100083 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Yong Liu
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
| | - Chenyi Shao
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Yuying Gao
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Fengtao Fan
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
| | - Junxi Wang
- Semiconductor Lighting Technology Research and Development CenterInstitute of SemiconductorsChinese Academy of Sciences Beijing 100083 China
| | - Jinmin Li
- Semiconductor Lighting Technology Research and Development CenterInstitute of SemiconductorsChinese Academy of Sciences Beijing 100083 China
| | - Janchang Yan
- Semiconductor Lighting Technology Research and Development CenterInstitute of SemiconductorsChinese Academy of Sciences Beijing 100083 China
| | - Rengui Li
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
| | - Can Li
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
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9
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El Hajraoui K, Robin E, Zeiner C, Lugstein A, Kodjikian S, Rouvière JL, Den Hertog M. In Situ Transmission Electron Microscopy Analysis of Copper-Germanium Nanowire Solid-State Reaction. NANO LETTERS 2019; 19:8365-8371. [PMID: 31613639 DOI: 10.1021/acs.nanolett.9b01797] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A promising approach of making high quality contacts on semiconductors is a silicidation (for silicon) or germanidation (for germanium) annealing process, where the metal enters the semiconductor and creates a low resistance intermetallic phase. In a nanowire, this process allows one to fabricate axial heterostructures with dimensions depending only on the control and understanding of the thermally induced solid-state reaction. In this work, we present the first observation of both germanium and copper diffusion in opposite directions during the solid-state reaction of Cu contacts on Ge nanowires using in situ Joule heating in a transmission electron microscope. The in situ observations allow us to follow the reaction in real time with nanometer spatial resolution. We follow the advancement of the reaction interface over time, which gives precious information on the kinetics of this reaction. We combine the kinetic study with ex situ characterization using model-based energy dispersive X-ray spectroscopy (EDX) indicating that both Ge and Cu diffuse at the surface of the created Cu3Ge segment and the reaction rate is limited by Ge surface diffusion at temperatures between 360 and 600 °C. During the reaction, germanide crystals typically protrude from the reacted NW part. However, their formation can be avoided using a shell around the initial Ge NW. Ha direct Joule heating experiments show slower reaction speeds indicating that the reaction can be initiated at lower temperatures. Moreover, they allow combining electrical measurements and heating in a single contacting scheme, rendering the Cu-Ge NW system promising for applications where very abrupt contacts and a perfectly controlled size of the semiconducting region is required. Clearly, in situ TEM is a powerful technique to better understand the reaction kinetics and mechanism of metal-semiconductor phase formation.
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Affiliation(s)
- Khalil El Hajraoui
- Université Grenoble Alpes , F-38000 Grenoble , France
- CNRS, Institut NEEL , F-38000 Grenoble , France
| | - Eric Robin
- Université Grenoble Alpes , F-38000 Grenoble , France
- CEA, INAC , F-38000 Grenoble , France
| | - Clemens Zeiner
- Institute of Solid State Electronics , TU-Wien - Nanocenter Campus Gußhaus , Gußhausstraße 25-25a , Gebäude-CH, A-1040 Wien , Austria
| | - Alois Lugstein
- Institute of Solid State Electronics , TU-Wien - Nanocenter Campus Gußhaus , Gußhausstraße 25-25a , Gebäude-CH, A-1040 Wien , Austria
| | - Stéphanie Kodjikian
- Université Grenoble Alpes , F-38000 Grenoble , France
- CNRS, Institut NEEL , F-38000 Grenoble , France
| | - Jean-Luc Rouvière
- Université Grenoble Alpes , F-38000 Grenoble , France
- CEA, INAC , F-38000 Grenoble , France
| | - Martien Den Hertog
- Université Grenoble Alpes , F-38000 Grenoble , France
- CNRS, Institut NEEL , F-38000 Grenoble , France
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10
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Li Z, Zhang L, Liu Y, Shao C, Gao Y, Fan F, Wang J, Li J, Yan J, Li R, Li C. Surface‐Polarity‐Induced Spatial Charge Separation Boosts Photocatalytic Overall Water Splitting on GaN Nanorod Arrays. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201912844] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Zheng Li
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Liang Zhang
- Semiconductor Lighting Technology Research and Development CenterInstitute of SemiconductorsChinese Academy of Sciences Beijing 100083 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Yong Liu
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
| | - Chenyi Shao
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Yuying Gao
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Fengtao Fan
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
| | - Junxi Wang
- Semiconductor Lighting Technology Research and Development CenterInstitute of SemiconductorsChinese Academy of Sciences Beijing 100083 China
| | - Jinmin Li
- Semiconductor Lighting Technology Research and Development CenterInstitute of SemiconductorsChinese Academy of Sciences Beijing 100083 China
| | - Janchang Yan
- Semiconductor Lighting Technology Research and Development CenterInstitute of SemiconductorsChinese Academy of Sciences Beijing 100083 China
| | - Rengui Li
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
| | - Can Li
- State Key Laboratory of CatalysisDalian National Laboratory for Clean EnergyDalian Institute of Chemical PhysicsChinese Academy of Sciences Dalian 116023 China
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11
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Cuesta S, Spies M, Boureau V, Donatini F, Hocevar M, den Hertog MI, Monroy E. Effect of Bias on the Response of GaN Axial p-n Junction Single-Nanowire Photodetectors. NANO LETTERS 2019; 19:5506-5514. [PMID: 31369282 DOI: 10.1021/acs.nanolett.9b02040] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We present a comprehensive study of the performance of GaN single-nanowire photodetectors containing an axial p-n junction. The electrical contact to the p region of the diode is made by including a p+/n+ tunnel junction as cap structure, which allows the use of the same metal scheme to contact both ends of the nanowire. Single-nanowire devices present the rectifying current-voltage characteristic of a p-n diode but their photovoltaic response to ultraviolet radiation scales sublinearly with the incident optical power. This behavior is attributed to the dominant role of surface states. Nevertheless, when the junction is reverse biased, the role of the surface becomes negligible in comparison to the drift of photogenerated carriers in the depletion region. Therefore, the responsivity increases by about 3 orders of magnitude and the photocurrent scales linearly with the excitation. These reverse-biased nanowires display decay times in the range of ∼10 μs, limited by the resistor-capacitor time constant of the setup. Their ultraviolet/visible contrast of several orders of magnitude is suitable for applications requiring high spectral selectivity. When the junction is forward biased, the device behaves as a GaN photoconductor with an increase of the responsivity at the price of a degradation of the time response. The presence of leakage current in some of the wires can be modeled as a shunt resistance which reacts to the radiation as a photoconductor and can dominate the response of the wire even under reverse bias.
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Affiliation(s)
- S Cuesta
- Université Grenoble-Alpes, CNRS-Institut Néel , 25 avenue des Martyrs , 38000 Grenoble , France
| | - M Spies
- Université Grenoble-Alpes, CNRS-Institut Néel , 25 avenue des Martyrs , 38000 Grenoble , France
| | - V Boureau
- Université Grenoble-Alpes, CNRS-Institut Néel , 25 avenue des Martyrs , 38000 Grenoble , France
| | - F Donatini
- Université Grenoble-Alpes, CNRS-Institut Néel , 25 avenue des Martyrs , 38000 Grenoble , France
| | - M Hocevar
- Université Grenoble-Alpes, CNRS-Institut Néel , 25 avenue des Martyrs , 38000 Grenoble , France
| | - M I den Hertog
- Université Grenoble-Alpes, CNRS-Institut Néel , 25 avenue des Martyrs , 38000 Grenoble , France
| | - E Monroy
- Université Grenoble-Alpes, CEA-IRIG-PHELIQS , 17 avenue des Martyrs , 38000 Grenoble , France
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12
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Zamani RR, Arbiol J. Understanding semiconductor nanostructures via advanced electron microscopy and spectroscopy. NANOTECHNOLOGY 2019; 30:262001. [PMID: 30812017 DOI: 10.1088/1361-6528/ab0b0a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Transmission electron microscopy (TEM) offers an ample range of complementary techniques which are able to provide essential information about the physical, chemical and structural properties of materials at the atomic scale, and hence makes a vast impact on our understanding of materials science, especially in the field of semiconductor one-dimensional (1D) nanostructures. Recent advancements in TEM instrumentation, in particular aberration correction and monochromation, have enabled pioneering experiments in complex nanostructure material systems. This review aims to address these understandings through the applications of the methodology for semiconductor nanostructures. It points out various electron microscopy techniques, in particular scanning TEM (STEM) imaging and spectroscopy techniques, with their already-employed or potential applications on 1D nanostructured semiconductors. We keep the main focus of the paper on the electronic and optoelectronic properties of such semiconductors, and avoid expanding it further. In the first part of the review, we give a brief introduction to each of the STEM-based techniques, without detailed elaboration, and mention the recent technological and conceptual developments which lead to novel characterization methodologies. For further reading, we refer the audience to a handful of papers in the literature. In the second part, we highlight the recent examples of application of the STEM methodology on the 1D nanostructure semiconductor materials, especially III-V, II-V, and group IV bare and heterostructure systems. The aim is to address the research questions on various physical properties and introduce solutions by choosing the appropriate technique that can answer the questions. Potential applications will also be discussed, the ones that have already been used for bulk and 2D materials, and have shown great potential and promise for 1D nanostructure semiconductors.
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Affiliation(s)
- Reza R Zamani
- Department of Physics, Chalmers University of Technology, Gothenburg, SE-41296, Sweden. Interdisciplinary Centre for Electron Microscopy (CIME), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
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13
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de la Mata M, Zamani RR, Martí-Sánchez S, Eickhoff M, Xiong Q, Fontcuberta I Morral A, Caroff P, Arbiol J. The Role of Polarity in Nonplanar Semiconductor Nanostructures. NANO LETTERS 2019; 19:3396-3408. [PMID: 31039314 DOI: 10.1021/acs.nanolett.9b00459] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The lack of mirror symmetry in binary semiconductor compounds turns them into polar materials, where two opposite orientations of the same crystallographic direction are possible. Interestingly, their physical properties (e.g., electronic or photonic) and morphological features (e.g., shape, growth direction, and so forth) also strongly depend on the polarity. It has been observed that nanoscale materials tend to grow with a specific polarity, which can eventually be reversed for very specific growth conditions. In addition, polar-directed growth affects the defect density and topology and might induce eventually the formation of undesirable polarity inversion domains in the nanostructure, which in turn will affect the photonic and electronic final device performance. Here, we present a review on the polarity-driven growth mechanism at the nanoscale, combining our latest investigation with an overview of the available literature highlighting suitable future possibilities of polarity engineering of semiconductor nanostructures. The present study has been extended over a wide range of semiconductor compounds, covering the most commonly synthesized III-V (GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb) and II-VI (ZnO, ZnTe, CdS, CdSe, CdTe) nanowires and other free-standing nanostructures (tripods, tetrapods, belts, and membranes). This systematic study allowed us to explore the parameters that may induce polarity-dependent and polarity-driven growth mechanisms, as well as the polarity-related consequences on the physical properties of the nanostructures.
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Affiliation(s)
- María de la Mata
- Catalan Institute of Nanoscience and Nanotechnology (ICN2) , CSIC and BIST , Campus UAB, Bellaterra , 08193 Barcelona, Catalonia , Spain
| | - Reza R Zamani
- Interdisciplinary Center for Electron Microscopy, CIME , École Polytechnique Fédérale de Lausanne (EPFL) , 1015 Lausanne , Switzerland
| | - Sara Martí-Sánchez
- Catalan Institute of Nanoscience and Nanotechnology (ICN2) , CSIC and BIST , Campus UAB, Bellaterra , 08193 Barcelona, Catalonia , Spain
| | - Martin Eickhoff
- Institute of Solid State Physics , University of Bremen , 28359 Bremen , Germany
| | - Qihua Xiong
- School of Physical and Mathematical Sciences , Nanyang Technological University , 637371 Singapore
| | | | - Philippe Caroff
- Microsoft Quantum Lab Delft, Delft University of Technology , 2600 GA Delft , The Netherlands
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology (ICN2) , CSIC and BIST , Campus UAB, Bellaterra , 08193 Barcelona, Catalonia , Spain
- ICREA , Pg. Lluís Companys 23 , 08010 Barcelona, Catalonia , Spain
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14
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El hajraoui K, Luong MA, Robin E, Brunbauer F, Zeiner C, Lugstein A, Gentile P, Rouvière JL, Den Hertog M. In Situ Transmission Electron Microscopy Analysis of Aluminum-Germanium Nanowire Solid-State Reaction. NANO LETTERS 2019; 19:2897-2904. [PMID: 30908919 PMCID: PMC6509643 DOI: 10.1021/acs.nanolett.8b05171] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 03/13/2019] [Indexed: 05/30/2023]
Abstract
To fully exploit the potential of semiconducting nanowires for devices, high quality electrical contacts are of paramount importance. This work presents a detailed in situ transmission electron microscopy (TEM) study of a very promising type of NW contact where aluminum metal enters the germanium semiconducting nanowire to form an extremely abrupt and clean axial metal-semiconductor interface. We study this solid-state reaction between the aluminum contact and germanium nanowire in situ in the TEM using two different local heating methods. Following the reaction interface of the intrusion of Al in the Ge nanowire shows that at temperatures between 250 and 330 °C the position of the interface as a function of time is well fitted by a square root function, indicating that the reaction rate is limited by a diffusion process. Combining both chemical analysis and electron diffraction we find that the Ge of the nanowire core is completely exchanged by the entering Al atoms that form a monocrystalline nanowire with the usual face-centered cubic structure of Al, where the nanowire dimensions are inherited from the initial Ge nanowire. Model-based chemical mapping by energy dispersive X-ray spectroscopy (EDX) characterization reveals the three-dimensional chemical cross-section of the transformed nanowire with an Al core, surrounded by a thin pure Ge (∼2 nm), Al2O3 (∼3 nm), and Ge containing Al2O3 (∼1 nm) layer, respectively. The presence of Ge containing shells around the Al core indicates that Ge diffuses back into the metal reservoir by surface diffusion, which was confirmed by the detection of Ge atoms in the Al metal line by EDX analysis. Fitting a diffusion equation to the kinetic data allows the extraction of the diffusion coefficient at two different temperatures, which shows a good agreement with diffusion coefficients from literature for self-diffusion of Al.
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Affiliation(s)
- Khalil El hajraoui
- Université
Grenoble Alpes, F-38000 Grenoble, France
- CNRS,
Institut NEEL, F-38000 Grenoble, France
| | - Minh Anh Luong
- Université
Grenoble Alpes, F-38000 Grenoble, France
- CEA,
INAC, F-38000 Grenoble, France
| | - Eric Robin
- Université
Grenoble Alpes, F-38000 Grenoble, France
- CEA,
INAC, F-38000 Grenoble, France
| | - Florian Brunbauer
- Institute
for Solid State Electronics, Vienna University
of Technology, Floragasse 7, 1040 Vienna, Austria
| | - Clemens Zeiner
- Institute
for Solid State Electronics, Vienna University
of Technology, Floragasse 7, 1040 Vienna, Austria
| | - Alois Lugstein
- Institute
for Solid State Electronics, Vienna University
of Technology, Floragasse 7, 1040 Vienna, Austria
| | - Pascal Gentile
- Université
Grenoble Alpes, F-38000 Grenoble, France
- CEA,
INAC, F-38000 Grenoble, France
| | - Jean-Luc Rouvière
- Université
Grenoble Alpes, F-38000 Grenoble, France
- CEA,
INAC, F-38000 Grenoble, France
| | - Martien Den Hertog
- Université
Grenoble Alpes, F-38000 Grenoble, France
- CNRS,
Institut NEEL, F-38000 Grenoble, France
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15
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Artioli A, Rueda-Fonseca P, Moratis K, Motte JF, Donatini F, Hertog MD, Robin E, André R, Niquet YM, Bellet-Amalric E, Cibert J, Ferrand D. Probing the light hole/heavy hole switching with correlated magneto-optical spectroscopy and chemical analysis on a single quantum dot. NANOTECHNOLOGY 2019; 30:175301. [PMID: 30650390 DOI: 10.1088/1361-6528/aaff17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A whole series of complementary studies have been performed on the same single nanowire containing a quantum dot: cathodoluminescence spectroscopy and imaging, micro-photoluminescence spectroscopy under magnetic field and as a function of temperature, and energy-dispersive x-ray spectrometry and imaging. The ZnTe nanowire was deposited on a Si3N4 membrane with Ti/Al patterns. The complete set of data shows that the CdTe quantum dot features the heavy-hole state as a ground state, although the compressive mismatch strain promotes a light-hole ground state as soon as the aspect ratio is larger than unity (elongated dot). A numerical calculation of the whole structure shows that the transition from the heavy-hole to the light-hole configuration is pushed toward values of the aspect ratio much larger than unity by the presence of a (Zn, Mg)Te shell, and that the effect is further enhanced by a small valence band offset between the semiconductors in the dot and around it.
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Affiliation(s)
- A Artioli
- Université Grenoble-Alpes, CNRS, Institut Néel, F-38000 Grenoble, France. Université Grenoble-Alpes, CEA, INAC, F-38000 Grenoble, France
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16
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Fu Y, Ding Y, Zheng L, Zhu Y, Han S. Morphology‐ and Size‐Controlled Fabrication of CdS from Flower‐Like to Spherical Structures and their Application for High‐Performance Photoactivity. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201801464] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Yimin Fu
- Department of Materials Science and Engineering University of Shanghai for Science and Technology 200093 Shanghai P.R. China
| | - Yuanpeng Ding
- Department of Materials Science and Engineering University of Shanghai for Science and Technology 200093 Shanghai P.R. China
| | - Lingxia Zheng
- Department of Applied Chemistry Zhejiang University of Technology 310032 Hangzhou P.R. China
| | - YuFang Zhu
- Department of Materials Science and Engineering University of Shanghai for Science and Technology 200093 Shanghai P.R. China
| | - Sancan Han
- Department of Materials Science and Engineering University of Shanghai for Science and Technology 200093 Shanghai P.R. China
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17
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Spies M, Polaczyński J, Ajay A, Kalita D, Luong MA, Lähnemann J, Gayral B, den Hertog MI, Monroy E. Effect of the nanowire diameter on the linearity of the response of GaN-based heterostructured nanowire photodetectors. NANOTECHNOLOGY 2018; 29:255204. [PMID: 29558360 DOI: 10.1088/1361-6528/aab838] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Nanowire photodetectors are investigated because of their compatibility with flexible electronics, or for the implementation of on-chip optical interconnects. Such devices are characterized by ultrahigh photocurrent gain, but their photoresponse scales sublinearly with the optical power. Here, we present a study of single-nanowire photodetectors displaying a linear response to ultraviolet illumination. Their structure consists of a GaN nanowire incorporating an AlN/GaN/AlN heterostructure, which generates an internal electric field. The activity of the heterostructure is confirmed by the rectifying behavior of the current-voltage characteristics in the dark, as well as by the asymmetry of the photoresponse in magnitude and linearity. Under reverse bias (negative bias on the GaN cap segment), the detectors behave linearly with the impinging optical power when the nanowire diameter is below a certain threshold (≈80 nm), which corresponds to the total depletion of the nanowire stem due to the Fermi level pinning at the sidewalls. In the case of nanowires that are only partially depleted, their nonlinearity is explained by a nonlinear variation of the diameter of their central conducting channel under illumination.
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Affiliation(s)
- Maria Spies
- University Grenoble-Alpes, CNRS, Institut Néel, 25 av. des Martyrs, F-38000 Grenoble, France
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18
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den Hertog M, Donatini F, McLeod R, Monroy E, Sartel C, Sallet V, Pernot J. In situ biasing and off-axis electron holography of a ZnO nanowire. NANOTECHNOLOGY 2018; 29:025710. [PMID: 28994395 DOI: 10.1088/1361-6528/aa923c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Quantitative characterization of electrically active dopants and surface charges in nano-objects is challenging, since most characterization techniques using electrons [1-3], ions [4] or field ionization effects [5-7] study the chemical presence of dopants, which are not necessarily electrically active. We perform cathodoluminescence and voltage contrast experiments on a contacted and biased ZnO nanowire with a Schottky contact and measure the depletion length as a function of reverse bias. We compare these results with state-of-the-art off-axis electron holography in combination with electrical in situ biasing on the same nanowire. The extension of the depletion length under bias observed in scanning electron microscopy based techniques is unusual as it follows a linear rather than square root dependence, and is therefore difficult to model by bulk equations or finite element simulations. In contrast, the analysis of the axial depletion length observed by holography may be compared with three-dimensional simulations, which allows estimating an n-doping level of 1 × 1018 cm-3 and negative sidewall surface charge of 2.5 × 1012 cm-2 of the nanowire, resulting in a radial surface depletion to a depth of 36 nm. We found excellent agreement between the simulated diameter of the undepleted core and the active thickness observed in the experimental data. By combining TEM holography experiments and finite element simulation of the NW electrostatics, the bulk-like character of the nanowire core is revealed.
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Affiliation(s)
- Martien den Hertog
- Université Grenoble Alpes, F-38000 Grenoble, France. Institut Néel CNRS, BP 166, 25 rue des Martyrs, F-38042 Grenoble, France
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19
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Lähnemann J, Ajay A, Den Hertog MI, Monroy E. Near-Infrared Intersubband Photodetection in GaN/AlN Nanowires. NANO LETTERS 2017; 17:6954-6960. [PMID: 28961016 DOI: 10.1021/acs.nanolett.7b03414] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Intersubband optoelectronic devices rely on transitions between quantum-confined electron levels in semiconductor heterostructures, which enables infrared (IR) photodetection in the 1-30 μm wavelength window with picosecond response times. Incorporating nanowires as active media could enable an independent control over the electrical cross-section of the device and the optical absorption cross-section. Furthermore, the three-dimensional carrier confinement in nanowire heterostructures opens new possibilities to tune the carrier relaxation time. However, the generation of structural defects and the surface sensitivity of GaAs nanowires have so far hindered the fabrication of nanowire intersubband devices. Here, we report the first demonstration of intersubband photodetection in a nanowire, using GaN nanowires containing a GaN/AlN superlattice absorbing at 1.55 μm. The combination of spectral photocurrent measurements with 8-band k·p calculations of the electronic structure supports the interpretation of the result as intersubband photodetection in these extremely short-period superlattices. We observe a linear dependence of the photocurrent with the incident illumination power, which confirms the insensitivity of the intersubband process to surface states and highlights how architectures featuring large surface-to-volume ratios are suitable as intersubband photodetectors. Our analysis of the photocurrent characteristics points out routes for an improvement of the device performance. This first nanowire based intersubband photodetector represents a technological breakthrough that paves the way to a powerful device platform with potential for ultrafast, ultrasensitive photodetectors and highly efficient quantum cascade emitters with improved thermal stability.
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Affiliation(s)
- Jonas Lähnemann
- Université Grenoble-Alpes, CEA, INAC, PHELIQS , 17 av. des Martyrs, 38000 Grenoble, France
| | - Akhil Ajay
- Université Grenoble-Alpes, CEA, INAC, PHELIQS , 17 av. des Martyrs, 38000 Grenoble, France
| | - Martien I Den Hertog
- Université Grenoble-Alpes, CNRS, Institut Néel , 25 av. des Martyrs, 38000 Grenoble, France
| | - Eva Monroy
- Université Grenoble-Alpes, CEA, INAC, PHELIQS , 17 av. des Martyrs, 38000 Grenoble, France
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20
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Ajay A, Lim CB, Browne DA, Polaczyński J, Bellet-Amalric E, Bleuse J, den Hertog MI, Monroy E. Effect of doping on the intersubband absorption in Si- and Ge-doped GaN/AlN heterostructures. NANOTECHNOLOGY 2017; 28:405204. [PMID: 28787278 DOI: 10.1088/1361-6528/aa8504] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this paper, we study band-to-band and intersubband (ISB) characteristics of Si- and Ge-doped GaN/AlN heterostructures (planar and nanowires) structurally designed to absorb in the short-wavelength infrared region, particularly at 1.55 μm. Regarding the band-to-band properties, we discuss the variation of the screening of the internal electric field by free carriers, as a function of the doping density and well/nanodisk size. We observe that nanowire heterostructures consistently present longer photoluminescence decay times than their planar counterparts, which supports the existence of an in-plane piezoelectric field associated to the shear component of the strain tensor in the nanowire geometry. Regarding the ISB characteristics, we report absorption covering 1.45-1.75 μm using Ge-doped quantum wells, with comparable performance to Si-doped planar heterostructures. We also report similar ISB absorption in Si- and Ge-doped nanowire heterostructures indicating that the choice of dopant is not an intrinsic barrier for observing ISB phenomena. The spectral shift of the ISB absorption as a function of the doping concentration due to many body effects confirms that Si and Ge efficiently dope GaN/AlN nanowire heterostructures.
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Affiliation(s)
- A Ajay
- Université Grenoble-Alpes, F-38000 Grenoble, France. CEA-Grenoble, INAC-PHELIQS, 17 av. des Martyrs, F-38000 Grenoble, France
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21
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Spies M, den Hertog MI, Hille P, Schörmann J, Polaczyński J, Gayral B, Eickhoff M, Monroy E, Lähnemann J. Bias-Controlled Spectral Response in GaN/AlN Single-Nanowire Ultraviolet Photodetectors. NANO LETTERS 2017; 17:4231-4239. [PMID: 28613893 DOI: 10.1021/acs.nanolett.7b01118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present a study of GaN single-nanowire ultraviolet photodetectors with an embedded GaN/AlN superlattice. The heterostructure dimensions and doping profile were designed in such a way that the application of positive or negative bias leads to an enhancement of the collection of photogenerated carriers from the GaN/AlN superlattice or from the GaN base, respectively, as confirmed by electron beam-induced current measurements. The devices display enhanced response in the ultraviolet A (≈ 330-360 nm)/B (≈ 280-330 nm) spectral windows under positive/negative bias. The result is explained by correlation of the photocurrent measurements with scanning transmission electron microscopy observations of the same single nanowire and semiclassical simulations of the strain and band structure in one and three dimensions.
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Affiliation(s)
- Maria Spies
- University Grenoble-Alpes , 38000 Grenoble, France
- CNRS-Institut Néel , 25 avenue des Martyrs, 38000 Grenoble, France
| | - Martien I den Hertog
- University Grenoble-Alpes , 38000 Grenoble, France
- CNRS-Institut Néel , 25 avenue des Martyrs, 38000 Grenoble, France
| | - Pascal Hille
- I. Physikalisches Institut, Justus Liebig Universität Gießen , Heinrich-Buff-Ring 16, 35390 Gießen, Germany
- Institut für Festkörperphysik, Universität Bremen , 28359 Bremen, Germany
| | - Jörg Schörmann
- I. Physikalisches Institut, Justus Liebig Universität Gießen , Heinrich-Buff-Ring 16, 35390 Gießen, Germany
| | - Jakub Polaczyński
- University Grenoble-Alpes , 38000 Grenoble, France
- CNRS-Institut Néel , 25 avenue des Martyrs, 38000 Grenoble, France
| | - Bruno Gayral
- University Grenoble-Alpes , 38000 Grenoble, France
- CEA-INAC-PHELIQS , 17 avenue des Martyrs, 38000 Grenoble, France
| | - Martin Eickhoff
- I. Physikalisches Institut, Justus Liebig Universität Gießen , Heinrich-Buff-Ring 16, 35390 Gießen, Germany
- Institut für Festkörperphysik, Universität Bremen , 28359 Bremen, Germany
| | - Eva Monroy
- University Grenoble-Alpes , 38000 Grenoble, France
- CEA-INAC-PHELIQS , 17 avenue des Martyrs, 38000 Grenoble, France
| | - Jonas Lähnemann
- University Grenoble-Alpes , 38000 Grenoble, France
- CEA-INAC-PHELIQS , 17 avenue des Martyrs, 38000 Grenoble, France
- Paul-Drude-Institut für Festkörperelektronik , Leibniz-Institut im Forschungsverbund Berlin e.V., Hausvogteiplatz 5-7, 10117 Berlin, Germany
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22
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Hetzl M, Kraut M, Hoffmann T, Stutzmann M. Polarity Control of Heteroepitaxial GaN Nanowires on Diamond. NANO LETTERS 2017; 17:3582-3590. [PMID: 28535070 DOI: 10.1021/acs.nanolett.7b00741] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Group III-nitride materials such as GaN nanowires are characterized by a spontaneous polarization within the crystal. The sign of the resulting sheet charge at the top and bottom facet of a GaN nanowire is determined by the orientation of the wurtzite bilayer of the different atomic species, called N and Ga polarity. We investigate the polarity distribution of heteroepitaxial GaN nanowires on different substrates and demonstrate polarity control of GaN nanowires on diamond. Kelvin Probe Force Microscopy is used to determine the polarity of individual selective area-grown and self-assembled nanowires over a large scale. At standard growth conditions, mixed polarity occurs for selective GaN nanowires on various substrates, namely on silicon, on sapphire and on diamond. To obtain control over the growth orientation on diamond, the substrate surface is modified by nitrogen and oxygen plasma exposure prior to growth, and the growth parameters are adjusted simultaneously. We find that the surface chemistry and the substrate temperature are the decisive factors for obtaining control of up to 93% for both polarity types, whereas the growth mode, namely selective area or self-assembled growth, does not influence the polarity distribution significantly. The experimental results are discussed by a model based on the interfacial bonds between the GaN nanowires, the termination layer, and the substrate.
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Affiliation(s)
- Martin Hetzl
- Walter Schottky Institut and Physics Department, Technische Universität München , 85748 Garching, Germany
| | - Max Kraut
- Walter Schottky Institut and Physics Department, Technische Universität München , 85748 Garching, Germany
| | - Theresa Hoffmann
- Walter Schottky Institut and Physics Department, Technische Universität München , 85748 Garching, Germany
| | - Martin Stutzmann
- Walter Schottky Institut and Physics Department, Technische Universität München , 85748 Garching, Germany
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23
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Roshko A, Brubaker MD, Blanchard PT, Bertness KA, Harvey TE, Geiss RH, Levin I. Comparison of convergent beam electron diffraction and annular bright field atomic imaging for GaN polarity determination. JOURNAL OF MATERIALS RESEARCH 2017; 32:10.1557/jmr.2016.443. [PMID: 31274956 PMCID: PMC6604648 DOI: 10.1557/jmr.2016.443] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A comparison of two electron microscopy techniques used to determine the polarity of GaN nanowires is presented. The techniques are convergent beam electron diffraction (CBED) in TEM mode and annular bright field (ABF) imaging in aberration corrected STEM mode. Both measurements were made at nominally the same locations on a variety of GaN nanowires. In all cases the two techniques gave the same polarity result. An important aspect of the study was the calibration of the CBED pattern rotation relative to the TEM image. Three different microscopes were used for CBED measurements. For all three instruments there was a substantial rotation of the diffraction pattern (120 or 180°) relative to the image, which, if unaccounted for, would have resulted in incorrect polarity determination. The study also shows that structural defects such as inversion domains can be readily identified by ABF imaging, but may escape identification by CBED. The relative advantages of the two techniques are discussed.
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Affiliation(s)
| | | | | | | | | | - Roy H. Geiss
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523
| | - Igor Levin
- Materials Measurement Science Division, NIST, Gaithersburg, MD 20899
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24
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Lähnemann J, Den Hertog M, Hille P, de la Mata M, Fournier T, Schörmann J, Arbiol J, Eickhoff M, Monroy E. UV Photosensing Characteristics of Nanowire-Based GaN/AlN Superlattices. NANO LETTERS 2016; 16:3260-7. [PMID: 27104371 DOI: 10.1021/acs.nanolett.6b00806] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We have characterized the photodetection capabilities of single GaN nanowires incorporating 20 periods of AlN/GaN:Ge axial heterostructures enveloped in an AlN shell. Transmission electron microscopy confirms the absence of an additional GaN shell around the heterostructures. In the absence of a surface conduction channel, the incorporation of the heterostructure leads to a decrease of the dark current and an increase of the photosensitivity. A significant dispersion in the magnitude of dark currents for different single nanowires is attributed to the coalescence of nanowires with displaced nanodisks, reducing the effective length of the heterostructure. A larger number of active nanodisks and AlN barriers in the current path results in lower dark current and higher photosensitivity and improves the sensitivity of the nanowire to variations in the illumination intensity (improved linearity). Additionally, we observe a persistence of the photocurrent, which is attributed to a change of the resistance of the overall structure, particularly the GaN stem and cap sections. As a consequence, the time response is rather independent of the dark current.
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Affiliation(s)
- Jonas Lähnemann
- University Grenoble-Alpes , 38000 Grenoble, France
- CEA-Grenoble, INAC-PHELIQS, 17 avenue des Martyrs, 38000 Grenoble, France
| | - Martien Den Hertog
- University Grenoble-Alpes , 38000 Grenoble, France
- Institut Nèel, CNRS, 25 avenue des Martyrs, 38000 Grenoble, France
| | - Pascal Hille
- I. Physikalisches Institut, Justus-Liebig-Universitt Gießen , 35392 Gießen, Germany
| | - Marı́a de la Mata
- Institut Catalá de Nanociència i Nanotecnologia (ICN2), CSIC and The Barcelona Institute of Science and Technology (BIST) , Campus UAB, Bellaterra, 08193 Barcelona, Catalonia, Spain
| | - Thierry Fournier
- University Grenoble-Alpes , 38000 Grenoble, France
- Institut Nèel, CNRS, 25 avenue des Martyrs, 38000 Grenoble, France
| | - Jörg Schörmann
- I. Physikalisches Institut, Justus-Liebig-Universitt Gießen , 35392 Gießen, Germany
| | - Jordi Arbiol
- Institut Catalá de Nanociència i Nanotecnologia (ICN2), CSIC and The Barcelona Institute of Science and Technology (BIST) , Campus UAB, Bellaterra, 08193 Barcelona, Catalonia, Spain
- Instituciò Catalana de Recerca i Estudis Avançats (ICREA), 08193 Barcelona, Catalonia, Spain
| | - Martin Eickhoff
- I. Physikalisches Institut, Justus-Liebig-Universitt Gießen , 35392 Gießen, Germany
| | - Eva Monroy
- University Grenoble-Alpes , 38000 Grenoble, France
- CEA-Grenoble, INAC-PHELIQS, 17 avenue des Martyrs, 38000 Grenoble, France
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25
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Du L, Wu Q, Pei X, Sun T, Zhang Y, Yang L, Wang X, Hu Z. Morphology and composition evolution of one-dimensional InxAl1−xN nanostructures induced by the vapour pressure ratio. CrystEngComm 2016. [DOI: 10.1039/c5ce01887k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Morphology and composition of one-dimensional alloyed InxAl1−xN nanostructures are regulated by tuning the vapour pressure ratio of InCl3 to AlCl3 during chemical vapour deposition.
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Affiliation(s)
- Lingyu Du
- Key Laboratory of Mesoscopic Chemistry of MOE and Collaborative Innovation Center of Chemistry for Life Sciences
- Jiangsu Provincial Laboratory for Nanotechnology
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023, China
| | - Qiang Wu
- Key Laboratory of Mesoscopic Chemistry of MOE and Collaborative Innovation Center of Chemistry for Life Sciences
- Jiangsu Provincial Laboratory for Nanotechnology
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023, China
| | - Xiaozhu Pei
- Key Laboratory of Mesoscopic Chemistry of MOE and Collaborative Innovation Center of Chemistry for Life Sciences
- Jiangsu Provincial Laboratory for Nanotechnology
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023, China
| | - Tao Sun
- Key Laboratory of Mesoscopic Chemistry of MOE and Collaborative Innovation Center of Chemistry for Life Sciences
- Jiangsu Provincial Laboratory for Nanotechnology
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023, China
| | - Yongliang Zhang
- Key Laboratory of Mesoscopic Chemistry of MOE and Collaborative Innovation Center of Chemistry for Life Sciences
- Jiangsu Provincial Laboratory for Nanotechnology
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023, China
| | - Lijun Yang
- Key Laboratory of Mesoscopic Chemistry of MOE and Collaborative Innovation Center of Chemistry for Life Sciences
- Jiangsu Provincial Laboratory for Nanotechnology
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023, China
| | - Xizhang Wang
- Key Laboratory of Mesoscopic Chemistry of MOE and Collaborative Innovation Center of Chemistry for Life Sciences
- Jiangsu Provincial Laboratory for Nanotechnology
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023, China
| | - Zheng Hu
- Key Laboratory of Mesoscopic Chemistry of MOE and Collaborative Innovation Center of Chemistry for Life Sciences
- Jiangsu Provincial Laboratory for Nanotechnology
- School of Chemistry and Chemical Engineering
- Nanjing University
- Nanjing 210023, China
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26
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Minj A, Cros A, Garro N, Colchero J, Auzelle T, Daudin B. Assessment of Polarity in GaN Self-Assembled Nanowires by Electrical Force Microscopy. NANO LETTERS 2015; 15:6770-6. [PMID: 26380860 DOI: 10.1021/acs.nanolett.5b02607] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In this work, we demonstrate the capabilities of atomic force microscopies (AFMs) for the nondestructive determination of the polarity of GaN nanowires (NWs). Three complementary AFMs are analyzed here: Kelvin probe force microscopy (KPFM), light-assisted KPFM, and piezo-force microscopy (PFM). These techniques allow us to assess the polarity of individual NWs over an area of tens of μm(2) and provide statistics on the polarity of the ensemble with an accuracy hardly reachable by other methods. The precise quantitative analysis of the tip-sample interaction by multidimensional spectroscopic measurements, combined with advanced data analysis, has allowed the separate characterization of electrostatic and van der Waals forces as a function of tip-sample distance. Besides their polarity, the net surface charge density of individual NWs was estimated.
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Affiliation(s)
- A Minj
- Materials Science Institute, University of Valencia , P.O. Box 22085, E46071 Valencia, Spain
| | - A Cros
- Materials Science Institute, University of Valencia , P.O. Box 22085, E46071 Valencia, Spain
| | - N Garro
- Materials Science Institute, University of Valencia , P.O. Box 22085, E46071 Valencia, Spain
| | - J Colchero
- Facultad de Química, Departamento de Física, Universidad de Murcia , 30100 Murcia, Spain
| | - T Auzelle
- Université Grenoble Alpes, INAC-SP2M , F-38000 Grenoble, France
- CEA, INAC-SP2M , F-38054 Grenoble, France
| | - B Daudin
- Université Grenoble Alpes, INAC-SP2M , F-38000 Grenoble, France
- CEA, INAC-SP2M , F-38054 Grenoble, France
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27
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Ogletree DF, Schuck PJ, Weber-Bargioni AF, Borys NJ, Aloni S, Bao W, Barja S, Lee J, Melli M, Munechika K, Whitelam S, Wickenburg S. Revealing Optical Properties of Reduced-Dimensionality Materials at Relevant Length Scales. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:5693-5719. [PMID: 26332202 DOI: 10.1002/adma.201500930] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 05/26/2015] [Indexed: 06/05/2023]
Abstract
Reduced-dimensionality materials for photonic and optoelectronic applications including energy conversion, solid-state lighting, sensing, and information technology are undergoing rapid development. The search for novel materials based on reduced-dimensionality is driven by new physics. Understanding and optimizing material properties requires characterization at the relevant length scale, which is often below the diffraction limit. Three important material systems are chosen for review here, all of which are under investigation at the Molecular Foundry, to illustrate the current state of the art in nanoscale optical characterization: 2D semiconducting transition metal dichalcogenides; 1D semiconducting nanowires; and energy-transfer in assemblies of 0D semiconducting nanocrystals. For each system, the key optical properties, the principal experimental techniques, and important recent results are discussed. Applications and new developments in near-field optical microscopy and spectroscopy, scanning probe microscopy, and cathodoluminescence in the electron microscope are given detailed attention. Work done at the Molecular Foundry is placed in context within the fields under review. A discussion of emerging opportunities and directions for the future closes the review.
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Affiliation(s)
- D Frank Ogletree
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
| | - P James Schuck
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
| | - Alexander F Weber-Bargioni
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
| | - Nicholas J Borys
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
| | - Shaul Aloni
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
| | - Wei Bao
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
- Materials Science and Engineering, University of California, Berkeley, California, 94720, USA
| | - Sara Barja
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
| | - Jiye Lee
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
| | - Mauro Melli
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
| | - Keiko Munechika
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
| | - Stephan Whitelam
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
| | - Sebastian Wickenburg
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720, USA
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28
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Hexagonal-like Nb₂O₅ nanoplates-based photodetectors and photocatalyst with high performances. Sci Rep 2015; 5:7716. [PMID: 25578788 PMCID: PMC4648379 DOI: 10.1038/srep07716] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 12/08/2014] [Indexed: 11/09/2022] Open
Abstract
Ultraviolet (UV) photodetectors are important tools in the fields of optical imaging, environmental monitoring, and air and water sterilization, as well as flame sensing and early rocket plume detection. Herein, hexagonal-like Nb₂O₅ nanoplates are synthesized using a facile solvothermal method. UV photodetectors based on single Nb₂O₅ nanoplates are constructed and the optoelectronic properties have been probed. The photodetectors show remarkable sensitivity with a high external quantum efficiency (EQE) of 9617%, and adequate wavelength selectivity with respect to UV-A light. In addition, the photodetectors exhibit robust stability and strong dependence of photocurrent on light intensity. Also, a low-cost drop-casting method is used to fabricate photodetectors based on Nb₂O₅ nanoplate film, which exhibit singular thermal stability. Moreover, the hexagonal-like Nb₂O₅ nanoplates show significantly better photocatalytic performances in decomposing Methylene-blue and Rhdamine B dyes than commercial Nb₂O₅.
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Beeler M, Hille P, Schörmann J, Teubert J, de la Mata M, Arbiol J, Eickhoff M, Monroy E. Intraband absorption in self-assembled Ge-doped GaN/AlN nanowire heterostructures. NANO LETTERS 2014; 14:1665-1673. [PMID: 24502703 DOI: 10.1021/nl5002247] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report the observation of transverse-magnetic-polarized infrared absorption assigned to the s-p(z) intraband transition in Ge-doped GaN/AlN nanodisks (NDs) in self-assembled GaN nanowires (NWs). The s-p(z) absorption line experiences a blue shift with increasing ND Ge concentration and a red shift with increasing ND thickness. The experimental results in terms of interband and intraband spectroscopy are compared to theoretical calculations of the band diagram and electronic structure of GaN/AlN heterostructured NWs, accounting for their three-dimensional strain distribution and the presence of surface states. From the theoretical analysis, we conclude that the formation of an AlN shell during the heterostructure growth applies a uniaxial compressive strain which blue shifts the interband optical transitions but has little influence on the intraband transitions. The presence of surface states with density levels expected for m-GaN plane charge-deplete the base of the NWs but is insufficient to screen the polarization-induced internal electric field in the heterostructures. Simulations show that the free-carrier screening of the polarization-induced internal electric field in the NDs is critical to predicting the photoluminescence behavior. The intraband transitions, on the other hand, are blue-shifted due to many-body effects, namely, the exchange interaction and depolarization shift, which exceed the red shift induced by carrier screening.
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Affiliation(s)
- M Beeler
- CEA-CNRS Group Nanophysics and Semiconductors, CEA/INAC/SP2M and CNRS-Institute Néel, 17 rue des Martyrs, 38054 Grenoble cedex 9, France
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30
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Shetty S, Ghatak J, Shivaprasad SM. Role of AlN intermediate layer in the morphological evolution of GaN nanorods grown on c-plane sapphire. CrystEngComm 2014. [DOI: 10.1039/c3ce42528b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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31
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Fernández-Garrido S, Kaganer VM, Sabelfeld KK, Gotschke T, Grandal J, Calleja E, Geelhaar L, Brandt O. Self-regulated radius of spontaneously formed GaN nanowires in molecular beam epitaxy. NANO LETTERS 2013; 13:3274-3280. [PMID: 23758601 DOI: 10.1021/nl401483e] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We investigate the axial and radial growth of GaN nanowires upon a variation of the Ga flux during molecular beam epitaxial growth. An increase in the Ga flux promotes radial growth without affecting the axial growth rate. In contrast, a decrease in the Ga flux reduces the axial growth rate without any change in the radius. These results are explained by a kinetic growth model that accounts for both the diffusion of Ga adatoms along the side facets toward the nanowire tip and the finite amount of active N available for the growth. The model explains the formation of a new equilibrium nanowire radius after increasing the Ga flux and provides an explanation for two well-known but so far not understood experimental facts: the necessity of effectively N-rich conditions for the spontaneous growth of GaN nanowires and the increase in nanowire radius with increasing III/V flux ratio.
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32
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Carnevale SD, Kent TF, Phillips PJ, Sarwar ATMG, Selcu C, Klie RF, Myers RC. Mixed polarity in polarization-induced p-n junction nanowire light-emitting diodes. NANO LETTERS 2013; 13:3029-3035. [PMID: 23756087 DOI: 10.1021/nl400200g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Polarization-induced nanowire light emitting diodes (PINLEDs) are fabricated by grading the Al composition along the c-direction of AlGaN nanowires grown on Si substrates by plasma-assisted molecular beam epitaxy (PAMBE). Polarization-induced charge develops with a sign that depends on the direction of the Al composition gradient with respect to the [0001] direction. By grading from GaN to AlN then back to GaN, a polarization-induced p-n junction is formed. The orientation of the p-type and n-type sections depends on the material polarity of the nanowire (i.e., Ga-face or N-face). Ga-face material results in an n-type base and a p-type top, while N-face results in the opposite. The present work examines the polarity of catalyst-free nanowires using multiple methods: scanning transmission electron microscopy (STEM), selective etching, conductive atomic force microscopy (C-AFM), and electroluminescence (EL) spectroscopy. Selective etching and STEM measurements taken in annular bright field (ABF) mode demonstrate that the preferred orientation for catalyst-free nanowires grown by PAMBE is N-face, with roughly 10% showing Ga-face orientation. C-AFM and EL spectroscopy allow electrical and optical differentiation of the material polarity in PINLEDs since the forward bias direction depends on the p-n junction orientation and therefore on nanowire polarity. Specifically, C-AFM reveals that the direction of forward bias for individual nanowire LEDs changes with the polarity, as expected, due to reversal of the sign of the polarization-induced charge. Electroluminescence measurements of mixed polarity PINLEDs wired in parallel show ambipolar emission due to the mixture of p-n and n-p oriented PINLEDs. These results show that, if catalyst-free III-nitride nanowires are to be used to form polarization-doped heterostructures, then it is imperative to understand their mixed polarity and to design devices using these nanowires accordingly.
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Affiliation(s)
- Santino D Carnevale
- Department of Materials Science and Engineering, ‡Department of Electrical and Computer Engineering, and §Department of Physics, Ohio State University, Columbus, Ohio 43210, United States
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